[Solved] No audio output with Focusrite Scarlett

[x42]

This is the output of adevices.sh (when Mixbus 32C is running (else card 1 is also "closed" but I guess thats normal).

yes, that's normal.

The output looks fine.

A buffersize of 64 with USB devices can be problematic and also Mixbus will use a lot of CPU.
It can work but it greatly depends on the hardware and system-tweaking if works reliably.

I'm curious what is the idle DSP load (indicator top-right in the Mixbus editor widow) with an empty session: just mixbusses + master?

That AlsaJsonMixer looks promising, I'll give it a look.

I did found some basic settings in alsamixer for the Scarlett but changing those settings did work.

I understand that you get sound, now, right?


All the mixer-controls should be there (supported by the driver in the kernel) 164 in total. `amixer --card 1 controls` list them.

When looking at those controls, it will help to visualize the signal-flow through this device:

   

"Matrix [01-18] Input" controls are for "Mixer Router" in that diagram. Each of the 18 inputs to the mixer-matrix can be assigned a source.
Possible values for each channel are the 6 DAW outputs (PCM1,6), any of the analog inputs (Analog 1..8) or the 10 Digital inputs (SPDIF, ADAT).

The matrix mixer's 18x6 grid is represented by the "Matrix [1-18] Mix [A-F] Playback Volume" gain controls where A,B,..,F are the 6 outputs and the inputs are the ones selected above.

The 6 "Master .. Source" control select which channels go into the Router.
Possible values are the same as above with addition of the matrix-mixer "Mix A,..F" outs.

Last but not least there are 6 master gain controls (5,6 is headphone) and a few switches for clock-source and impedance.

It's definitely easier to use a GUI for a DAW setup, then again this devices allow for fancy zero-latency mixing, some combinations of which are not even exposed by Scarlett Mixcontrol ™.

PS. I'm not sure if the the 18 "Input Source" capture assignments currently do anything, They are for the built-in meters which the alsa-team decided to not expose via the mixer-interface.

[Patrick Kox]

Finally got it working ! (Now I need to see if it survives a reboot ).

Installing the Gateway was a breeze, the Mixer was a bit harder.
Both had some dependency issues that I needed to sort out, and I had to restart the gateway to be able to get the Mixer to show/work in Iceweasel.

I've added some screenshots.

[Image: ajm-Alsa-Mixer%20-%20Iceweasel_001.png]

[Image: ajm-Alsa-Mixer%20-%20Iceweasel_002.png]

I think the things I needed to change were.

- increase volume "Playback Master Volume) since they were at zero
- Set "Master Playback Route" to All at PCM1 for Left and PCM2 for right (since Mixbus only exported to those 2 ports).
- Toggle the " Playback Switch to mute/un-mute some of the outputs).

I hope this helps other people since I've spent a few days searching for the correct answer.

Kudos to x42 for pointing me in the right direction, and also thanks to the other members who contributed to this thread.

Patrick

---

This is the output of adevices.sh (when Mixbus 32C is running (else card 1 is also "closed" but I guess thats normal).

yes, that's normal.

The output looks fine.

A buffersize of 64 with USB devices can be problematic and also Mixbus will use a lot of CPU.
It can work but it greatly depends on the hardware and system-tweaking if works reliably.

I'm curious what is the idle DSP load (indicator top-right in the Mixbus editor widow) with an empty session: just mixbusses + master?

That AlsaJsonMixer looks promising, I'll give it a look.

I did found some basic settings in alsamixer for the Scarlett but changing those settings did work.

I understand that you get sound, now, right?


All the mixer-controls should be there (supported by the driver in the kernel) 164 in total. `amixer --card 1 controls` list them.

When looking at those controls, it will help to visualize the signal-flow through this device:



"Matrix [01-18] Input" controls are for "Mixer Router" in that diagram. Each of the 18 inputs to the mixer-matrix can be assigned a source.
Possible values for each channel are the 6 DAW outputs (PCM1,6), any of the analog inputs (Analog 1..8) or the 10 Digital inputs (SPDIF, ADAT).

The matrix mixer's 18x6 grid is represented by the "Matrix [1-18] Mix [A-F] Playback Volume" gain controls where A,B,..,F are the 6 outputs and the inputs are the ones selected above.

The 6 "Master .. Source" control select which channels go into the Router.
Possible values are the same as above with addition of the matrix-mixer "Mix A,..F" outs.

Last but not least there are 6 master gain controls (5,6 is headphone) and a few switches for clock-source and impedance.

It's definitely easier to use a GUI for a DAW setup, then again this devices allow for fancy zero-latency mixing, some combinations of which are not even exposed by Scarlett Mixcontrol ™.

PS. I'm not sure if the the 18 "Input Source" capture assignments currently do anything, They are for the built-in meters which the alsa-team decided to not expose via the mixer-interface.

x42 I see we were both replying at the same time. But to answer your questions/remarques

1. Buffer size 64 :
I've set mixbus to halt on xrun and it didn't stop yet so I guess it works. But as I said I try to run nothing else on this system (plain Debian 8.4 with Openbox so no Gnome, KDE, ... running).

2. idle DSP load is around 25%

3. I didn't have sound when I replied (before I installed the Gateway and Mixer) but I guess that's because The "Playback" settings were output 1 -> Analog 1 ,output 2 -> Analog 2 and so on, While with the HTML5 mixer I had to set them to PCM1 for Left and PCM2 for Right.

4. Thanks for all the information.
I'll keep it stored somewhere incase I need it again in the future.

[x42]

Cool.

I just saw 18i8 (not 18i6) but the routing is pretty much the same (only 8 instead of 6 PCM + MIx channels for the internal router). I don't know how the web-interface GUI translates the 0..128 gain to the soundcard's settings, but all the way to the top is probably +6dB in which case ~100 corresponds to "0dB". (you can check with `alsamixer` which does show dB Levels).

[eudoxos]

Thanks for the mixer. I had to finish the configuration by unmuting Master (and also Master 2 for Headphones in my case) by hand in alsamixer. Is the mute switch exposed in the UI? Could not find it. Thanks!